JP2020021676A - Alkaline battery - Google Patents

Abstract

To provide an alkaline battery capable of suppressing liquid leakage.SOLUTION: An alkaline battery includes: a battery case; a power generation element housed in the battery case; and a sealing unit. The sealing unit includes: a negative electrode terminal plate; an anode current collector joined to the negative electrode terminal plate; and a gasket. The gasket has a thin part that has an explosion-proof function at the connecting part that connects a boss part and an outer peripheral part. An inner surface opposing the power generation element of the gasket has a first area where a water-repellent layer is formed and a second area where no water-repellent layer is formed. A second region is located at an outer peripheral side of a first position Q1 on the inner surface of the joint, and Q1 is located on a contact area S between a connection part and a separator or is located at an inner peripheral side of the contact area S and a separation distance from the contact area S is within 1 mm. The first area includes an area that is located at the inner peripheral side of Q1 and whose height based on a bottom of the battery case is equal to or higher than a height H1 of Q1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an alkaline battery.

  The alkaline dry battery includes a battery case having an opening, a power generation element housed in the battery case, and a sealing unit for closing the opening of the battery case. The sealing unit includes a negative electrode terminal plate, a negative electrode current collector joined to the negative electrode terminal plate, and a gasket. The gasket includes a boss for penetrating the negative electrode current collector, an outer peripheral portion in contact with the opening end of the battery case, and a connecting portion for connecting the boss and the outer peripheral portion. A thin portion having an explosion-proof function is formed in the connecting portion.

  If the battery is misused, the internal pressure of the battery may rise abnormally. When the battery internal pressure rises abnormally, the connecting portion expands toward the negative electrode terminal plate, tension is applied to the thin portion, and the thin portion breaks. As a result, the gas generated in the battery is discharged out of the battery from the gas vent holes formed in the negative electrode terminal plate. Therefore, the safety of the battery is ensured.

  Japanese Patent Application Laid-Open No. H11-163873 discloses that the entire surface of a polyamide resin gasket is covered with a thin film layer made of synthetic rubber to prevent deterioration of the gasket and improve long-term storage characteristics of an alkaline dry battery.

  Patent Literature 2 discloses that by covering a predetermined breaking point of a sealing member with a non-porous film, corrosion of the sealing member caused by contact with an electrolyte is prevented, and a decrease in mechanical strength at the predetermined breaking point is suppressed. It is. Examples of the coating material include bitumen, fatty acid polyamide, and alkali-resistant lacquer.

JP 2014-53299 A JP-A-63-202844

  When the alkaline dry battery reaches an overdischarged state, the metal (eg, copper) constituting the current collector may be dissolved in the negative electrode, and hydrogen gas may be generated. However, by providing the thin portion in the inner peripheral region, the generated hydrogen gas can be transmitted through the thin portion. Thus, an increase in internal pressure due to generation of hydrogen gas during overdischarge can be suppressed.

  However, in the overdischarged state, the negative electrode active material is in an expanded state, so that the remaining electrolyte moves in the gasket direction and easily fills the concave portion of the gasket formed by the thin portion. If the concave space is completely filled with the electrolytic solution or at least the inner surface of the concave portion is covered with the electrolytic solution, hydrogen permeation through the thin portion is hindered by the electrolytic solution, and the effect of suppressing the increase in the internal pressure is hindered. obtain. As a result, the alkaline dry battery may leak.

One aspect of the present invention includes a battery case having an opening, a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and a power generation element housed in the battery case, And a closing unit for closing the opening,
The sealing unit includes a negative electrode terminal plate, a negative electrode current collector joined to the negative electrode terminal plate, and a gasket,
The gasket includes a boss portion through which the negative electrode current collector penetrates, an outer peripheral portion in contact with an opening end of the battery case, and a connecting portion that connects the boss portion and the outer peripheral portion,
The connecting portion has a thin portion having an explosion-proof function,
A water-repellent layer is formed on an inner surface of the gasket facing the power generation element,
The inner surface of the gasket has a first region where the water-repellent layer is formed, and a second region where the water-repellent layer is not formed,
The first region includes an inner surface of the thin portion, and is located on an inner peripheral side of a first position Q1 on the inner surface of the connecting portion,
The second region is located on the outer peripheral side of the first position Q1,
When the height in the axial direction of the boss portion with respect to the bottom portion of the battery case at the first position Q1 is H1, the first region is located on the inner peripheral side with respect to the first position Q1, And including a region located at a height equal to or higher than H1;
The first position Q1 is located on a contact area S on the inner surface between the connecting portion and the separator, or the first position Q1 is located on the inner peripheral side of the contact area S and the The distance between the one position Q1 and the contact area S is within 1 mm,
The contact angle theta ₁ with respect to water of the water-repellent layer is greater than the contact angle theta ₂ with respect to water of the gasket, it relates to an alkaline dry battery.

  In an alkaline dry battery, liquid leakage due to generation of hydrogen gas during overdischarge is suppressed.

It is a half sectional view showing an example of the internal structure of the alkaline dry battery concerning the embodiment of the present invention. It is a fragmentary sectional view showing an example of the structure of the closure unit concerning the embodiment of the present invention. FIG. 7 is a diagram illustrating a region where a water-repellent layer is formed on an inner surface of a gasket in each embodiment.

  An alkaline dry battery according to an embodiment of the present invention includes a battery case having an opening, a power generating element housed in the battery case, and a sealing unit for closing the opening of the battery case. The power generating element has a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and is housed in a battery case. The sealing unit includes a negative electrode terminal plate, a negative electrode current collector joined to the negative electrode terminal plate, and a gasket. The gasket includes a boss for penetrating the negative electrode current collector, an outer peripheral portion in contact with the opening end of the battery case, and a connecting portion for connecting the boss and the outer peripheral portion. The connecting portion has a thin portion having an explosion-proof function.

  As a material of the gasket, for example, polyamide resin such as 6,6-nylon, 6,10-nylon, 6,12-nylon is used. From the viewpoint of hydrogen permeability, it is more preferable to use 6,10-nylon or 6,12-nylon.

A water-repellent layer is formed on the inner surface of the gasket facing the power generating element. The contact angle theta ₁ with respect to water of the water-repellent layer is greater than the contact angle theta ₂ with respect to water of the gasket.
The water-repellent layer is provided in a predetermined region on a part of the inner surface of the gasket. In the alkaline dry battery of the present embodiment, by controlling the region where the water-repellent layer is formed within a specific range including the inner surface of the thin portion, it is possible to prevent the electrolytic solution from adhering to the surface of the thin portion. Furthermore, even when the negative electrode expands due to overdischarge, a space in which no electrolyte is present can be secured on the inner surface of the thin portion. The hydrogen gas generated by the overdischarge can escape from this space to the outside of the battery via the thin film portion, so that the internal pressure rise due to the generation of the hydrogen gas is suppressed.

  The water-repellent layer can be formed not only on the inner surface of the connecting portion but also on the outer peripheral wall surface and the lower wall surface of the boss portion. The inner surface of the gasket facing the power generating element includes the inner surface of the connecting portion, the outer peripheral wall surface and the lower wall surface of the boss portion. On the inner surface of the gasket, a region where the water-repellent layer is formed is defined as a first region, and a region where the water-repellent layer is not formed is defined as a second region.

  The first region is a region that includes the inner surface of the thin portion and is located on the inner peripheral side of the first position Q1 on the inner surface of the connecting portion. The second area is an area located on the outer peripheral side of the first position Q1. Here, the first position Q1 is on a contact area S between the connecting portion and the separator. Alternatively, the first position Q1 may be located on the inner peripheral side of the contact area S, but in this case, the distance between the first position Q1 and the contact area S is within 1 mm. Therefore, a water-repellent layer is not formed on a region of the inner surface of the connecting portion that faces the positive electrode on the outer peripheral side of the separator.

  Here, the height in the axial direction of the boss with respect to the bottom of the battery case at the first position Q1 is defined as H1. The first region includes a region located on the inner peripheral side with respect to the first position Q1 and located at a height equal to or higher than H1. In the following, the term “height” simply refers to the height of the boss in the axial direction with respect to the bottom of the battery case.

  On the inner surface of the gasket, a region where the water-repellent layer is provided exists in a region facing the negative electrode on the inner peripheral side of the separator. A water-repellent layer is formed on the inner surface at least in a region where the height in the axial direction of the boss with respect to the bottom of the battery case is H1 or more.

  When the positive and negative electrode active materials expand due to overdischarge or the like, the electrolyte is pushed out by the positive and negative electrode active materials, and the liquid level of the electrolyte rises toward the gasket side. As a result, the electrolyte easily adheres to the inner surface of the gasket, but since the water-repellent layer is provided in the first region on the inner surface facing the negative electrode, the electrolyte hardly adheres.

  On the other hand, since the water-repellent layer is not provided on the inner surface facing the positive electrode, the extruded electrolytic solution is more on the positive electrode side where the water-repellent layer is not provided than on the negative electrode side where the water-repellent layer is provided. Easy to move and stay. By providing the water-repellent layer on the inner surface of the gasket on the negative electrode side, but not on the inner surface of the gasket on the positive electrode side, the movement of the electrolytic solution to the positive electrode side is promoted. It becomes difficult to rise above. Therefore, a space in which the electrolyte does not exist can be secured on the inner surface of the thin portion.

  With this configuration, hydrogen gas that can be generated at the time of overdischarge can escape to the outside of the battery via the thin portion, and an increase in internal pressure due to generation of hydrogen gas is suppressed. Therefore, liquid leakage at the time of overdischarge is suppressed.

  The water-repellent layer may be formed in a region located on the inner peripheral side of the first position Q1 and having a height lower than H1. This makes it easier for the electrolytic solution to move to the positive electrode side, and it is easier to secure a space where no electrolytic solution exists on the inner surface of the thin portion.

For example, even when a part of the outer peripheral wall surface of the boss is exposed so as to be able to come into contact with the electrolytic solution, a water-repellent layer is formed at least in a region where the height of the outer peripheral wall surface is equal to or higher than H1. Of course, the water-repellent layer may be formed also in a region where the height of the outer peripheral wall surface is lower than H1 (more preferably, on the entire outer peripheral wall surface).
On the inner surface of the gasket, let P be the boundary position between the boss and the connection. In one embodiment (see FIG. 2 to be described later), the water-repellent layer is a region (for example, annular) in which the boundary position P is the inner peripheral end and the first position Q1 is the outer peripheral end on the inner surface of the connecting portion. Can be formed. In addition, the water-repellent layer may be formed on the outer peripheral wall surface of the boss portion in a cylindrical region from the boundary position P to the second position Q2 on the outer peripheral wall surface of the boss portion. When the height of the second position Q2 is H2, H2 is equal to or less than H1. The height H2 is preferably lower than H1.

  It is also possible to provide a reinforcing rib on the inner surface side of the connecting portion to increase the strength of the gasket. In that case, the connecting portion is thickened in a part of the circumferential direction, and the boundary position P between the boss portion and the connecting portion may change depending on the circumferential direction of the boss portion. In a part of the circumferential direction, the height of the boundary position P is lower than the height H1 of the first position Q1 and is located on the power generation element side, or in a part of the region on the inner peripheral side with respect to the gasket Q1. It is also conceivable that the height of the inner surface is lower than H1. In this case, the water-repellent layer only needs to be provided in a region on the inner peripheral side with respect to Q1 and the height of the gasket inner surface is equal to or higher than H1. The water-repellent layer may not be formed in a region on the inner peripheral side of Q1 and the height of the gasket inner surface is less than H1. However, from the viewpoint of promoting the movement of the electrolytic solution to the positive electrode side, it is necessary to form the water-repellent layer also in a region located on the inner peripheral side from the first position Q1 and a height lower than H1. Is preferred.

  It is preferable that the water-repellent layer is formed so as to satisfy the above relationship over the entire circumference in the circumferential direction.

The water-repellent layer, the contact angle theta ₁ with respect to water is greater than the contact angle theta ₂ with respect to water of the gasket, as long as it can be formed on the gasket is not particularly limited. The water-repellent layer is preferably made of a material having alkali resistance. The ratio of the contact angle theta ₂ to the contact angle theta ₁ is preferably θ ₂ / θ ₁ is 0.9 or less, more preferably 0.75 or less.

For example, when using 6,12-nylon (θ ₂ = 70 °) for the gasket, a gasket having θ ₁ exceeding 70 ° can be used. theta ₁ and more preferably not less than 90 °. Examples of such materials include polypropylene (θ ₁ = 94 °), bitumen (θ ₁ = 105 °), fatty acids, and fluororesins. Fatty acids include stearic acid (θ ₁ = 95 °). Examples of the fluorine-based resin include ethylene tetrafluoride-perfluoroalkoxyethylene copolymer (PFA) (θ ₁ = 115 °), ethylene tetrafluoride polymer (PTFE) (θ ₁ = 114 °), and ethylene tetrafluoride. -Propylene hexafluoride copolymer (FEP) (θ ₁ = 114 °), ethylene tetrafluoride-propylene copolymer rubber (FEPM) (θ ₁ = 105 °), ethylene tetrafluoride / ethylene copolymer ( ETFE) (θ ₁ = 96 °) or the like can be used.

To form the water-repellent layer in the first region, the contact angle theta ₁ is a dispersion prepared by dispersing to prepare a large water repellent material in the dispersion medium than the contact angle theta _2, coating the dispersion on the inner surface of the gasket A way is possible. The dispersion may be dropped on the inner surface of the gasket while the gasket is rotated in the axial direction of the boss. The region where the water-repellent layer is formed can be controlled by adjusting the drop amount and the rotation speed. The water-repellent layer may be formed by a method such as applying or spraying a dispersion while the second region is masked with a mold or the like.

  In the present embodiment, the shape and size of the alkaline dry battery are not limited. In particular, in the AA (LR6) embodiment, the internal pressure rise due to the generation of hydrogen gas is suppressed, The effect of suppressing is large. The use of the alkaline dry battery is not limited, but particularly when used as a power supply for an LED light, since it can be lit even at an extremely low current, it is difficult to stop the discharge even in an overdischarge state. As a result, since the negative electrode active material expands more at the time of overdischarge, the remaining electrolyte moves in the gasket direction, easily fills the concave portion formed by the thin portion, and the problem of liquid leakage due to generation of hydrogen gas is more likely to occur. With the configuration of the water-repellent layer of the present embodiment, liquid leakage due to generation of hydrogen gas during overdischarge can be suppressed.

  Hereinafter, embodiments of the present invention will be further described with reference to the drawings. Note that the present invention is not limited to the following embodiments.

  FIG. 1 is a half sectional view showing an example of an internal structure of an alkaline dry battery 100 according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view illustrating an example of the structure of the sealing unit according to the embodiment. 1 and 2 (and FIG. 3 to be described later), the water-repellent layer 11 is drawn thicker than it actually is in order to emphasize the mode of the water-repellent layer 11.

  The positive electrode 2 and the gelled negative electrode 3 are housed in the bottomed cylindrical battery case 1 via a separator 4. The battery case 1 is obtained, for example, by pressing a nickel-plated steel plate into a predetermined shape. A conductive coating may be formed on the inner surface of the battery case 1.

  The opening of the battery case 1 is sealed by a sealing unit 9 in which the negative electrode terminal plate 5, the negative electrode current collector 6, and the gasket 7 are integrally assembled. The negative electrode terminal plate 5 is obtained by, for example, press-forming a nickel-plated steel plate or a tin-plated steel plate into a predetermined shape. A gas vent hole (not shown) for letting gas escape to the outside when the explosion-proof function by the thin portion 8 of the gasket 7 is activated is provided in the peripheral portion of the negative electrode terminal plate 5. A flange 6 a is formed at an end of the negative electrode current collector 6, and the flange 6 a is joined to the negative electrode terminal plate 5 by welding. The negative electrode current collector 6 is obtained by, for example, pressing a brass wire into a nail shape having a predetermined dimension. The outer peripheral surface of the battery case 1 is covered with an exterior label 10.

  The gasket 7 has a boss 7a, an outer peripheral portion 7b, and an annular connecting portion 7c connecting the boss 7a and the outer peripheral portion 7b. The boss 7 a of the gasket 7 penetrates the negative electrode current collector 6. An outer peripheral portion 7 b of the gasket is in contact with the opening end of the battery case 1 so as to be sandwiched therebetween, and is caulked to the peripheral edge of the negative electrode terminal plate 5. The connecting portion 7c of the gasket has a thin portion 8 having an explosion-proof function in an inner peripheral area near the boss 7a. The minimum thickness of the thin portion 8 is set, for example, to 0.10 mm to 0.35 mm. As a material of the gasket 7, for example, a polyamide resin such as 6,10-nylon and 6,12-nylon is used. Due to the thin portion 8, a concave portion is formed on the inner surface of the connecting portion 7c facing the power generating element.

  A water-repellent layer 11 is formed on the inner surface of the gasket 7. The water-repellent layer 11 extends over the annular region having the inner surface position Q1 of the connecting portion 7c as the outer peripheral end and the boundary position P between the boss 7a and the connecting portion 7c as the inner peripheral end. Covering the surface. The water-repellent layer 11 also covers the outer wall surface of the boss 7a in the axial direction of the boss 7a over a cylindrical region from the boundary position P to a position Q2 on the outer peripheral wall surface of the boss 7a. On the other hand, no water-repellent layer is provided on the inner surface of the connecting portion 7c located on the outer peripheral side of Q1.

  The separator 4 is in contact with the connecting portion 7c in the contact area S. In the example of FIG. 2, the position Q1 is located on the inner periphery of the contact area S and is separated from the contact area S, but the separation distance is within 1 mm. The height at the position Q1 with reference to the bottom of the battery case 1 is H1. On the inner surface of the gasket facing the negative electrode 3, at least a region having a height of H1 or more is covered with the water-repellent layer 11. On the other hand, the water-repellent layer 11 is not formed on the inner surface of the gasket facing the positive electrode 2. Thereby, even when the electrolytic solution is extruded due to the expansion of the positive and negative electrode active materials and the electrolytic solution easily comes into contact with the inner surface, the electrolytic solution is more likely to stay on the positive electrode side than on the negative electrode side. The liquid level of the liquid hardly rises above H1. As a result, in the concave portion formed by the thin portion 8, a space in which the electrolytic solution does not exist can be secured, and the leakage is suppressed.

  In the example of FIG. 2, the water-repellent layer 11 is formed on the outer peripheral wall surface of the boss portion 7a from the position P to a position Q2 lower than the position Q1. As a result, the effect of retaining the electrolytic solution on the positive electrode side can be enhanced, and a space in which the electrolytic solution does not exist on the inner surface of the thin portion is easily secured.

  In the example of FIG. 2, the connecting portion 7c of the gasket is connected to the boss portion 7a so that the outer peripheral side is closer to the power generating element than the inner peripheral side. When the connecting portion 7c is inclined as described above, the inner surface of the thin portion 8 may be the highest point in the first region on the inner surface of the connecting portion 7c where the water-repellent layer 11 is formed. For this reason, even when the electrolytic solution is extruded due to the expansion of the negative electrode active material and the level of the electrolytic solution rises, it is easy to secure a space where the electrolytic solution does not exist in the concave space on the inner surface of the thin portion 8. Therefore, the effect of providing the water-repellent layer 11 in the first region is easily exerted.

  In the example of FIG. 2, the thin portion 8 is provided in an inner peripheral area adjacent to the boss 7 a of the connecting portion 7 c, and the connecting portion 7 c is connected to the boss 7 a at the thin portion 8. In this case, the connecting portion 7c is connected perpendicularly to the boss portion 7a and the axis of the boss portion, or is connected to the boss portion 7a such that the outer peripheral side is closer to the power generating element than the inner peripheral side as described above. Thus, in the first region, the inner surface of the thin portion 8 is the highest point. Therefore, the effect of providing the water-repellent layer 11 in the first region is easily exerted.

  In the illustrated example, the skirt angle (the angle between the opening side surface of the connecting portion 7c (thin portion 8) in the cross section of the gasket and the height direction of the boss portion) α is preferably 45 ° or more and 90 ° or less, and 50 ° or less. It is more preferably at least 85 degrees and not more than 85 degrees.

  The width of the thin portion 8 (the distance from the outermost peripheral position to the innermost peripheral position of the thinnest region in the connecting portion 7c) is, for example, 0.3 mm to 1.times. 2 mm.

  The body diameter of the negative electrode current collector 6 is, for example, preferably 2.0 mm or less, and more preferably 1.8 mm or less. In addition, from the viewpoint of ensuring excellent current collecting performance, the body diameter of the negative electrode current collector 6 is preferably equal to or greater than 1.1 mm, and more preferably equal to or greater than 1.15 mm.

  The outer diameter of the boss is preferably, for example, 3.0 mm to 4.5 mm. The outer diameter of the outer peripheral portion 7b of the gasket is determined by the size of the battery.

  A sealant may be interposed between the negative electrode current collector 6 and the boss 7a. The sealing agent makes it difficult for the alkaline electrolyte to leak from between the negative electrode current collector and the boss. As the sealant, a silicone resin, a fluorine resin, an epoxy resin to which polyamidoamine is added, or the like can be used.

Hereinafter, the specific configuration of the power generating element of the alkaline dry battery will be further described.
For the positive electrode 2, for example, a molded product of a mixture containing a positive electrode active material, a conductive agent, and an alkaline electrolyte is used. Binders such as polyethylene powder and lubricants such as stearates may be added to the mixture. Manganese dioxide powder, nickel oxyhydroxide powder, or the like is used as the positive electrode active material. Graphite powder or the like is used as the conductive agent.

  For the gelled negative electrode 3, for example, a mixture containing a negative electrode active material, an alkaline electrolyte and a gelling agent is used. A zinc alloy powder is used for the negative electrode active material. As the gelling agent, sodium polyacrylate or the like is used. In order to improve the corrosion resistance of the zinc alloy, a metal compound having a high hydrogen overvoltage such as indium or bismuth or a surfactant may be added to the mixture.

  For the separator 4, for example, a nonwoven fabric mainly composed of polyvinyl alcohol fiber and rayon fiber is used.

  Each of the positive electrode 2, the gelled negative electrode 3, and the separator 4 contains an alkaline electrolyte. As the alkaline electrolyte, for example, an aqueous solution containing 30 to 40% by mass of potassium hydroxide and 1 to 3% by mass of zinc oxide is used.

  Hereinafter, embodiments of the present invention will be further described based on examples, but the present invention is not limited to the examples. Here, an AA alkaline battery having a structure as shown in FIG. 1 was manufactured.

<< Example 1 >>
(1) Production of Sealing Unit A gasket 7 having a thin portion 8 was produced by injection molding 6,12-nylon into a predetermined shape using a mold. The thickness of the connecting portion 7c in the region not thinned was 0.75 mm, and the thinnest minimum thickness of the thin portion was 0.22 mm. The width in the radial direction of the region where the thickness of the thin portion was 0.22 mm was 0.45 mm. No reinforcing rib was formed on the opening side surface of the connecting portion 7c of the gasket 7. The skirt angle α was 78 degrees.

  A dispersion in which a water-repellent material was dispersed in a dispersion medium was prepared, and the dispersion was applied to a predetermined region on the inner surface of a gasket, and then dried to form a water-repellent layer. The region for forming the water-repellent layer and the dispersion medium used for preparing the dispersion will be described later.

  Brass with a copper content of 58% by mass was processed into a nail shape with a total length of 30 mm and a body diameter of 1.20 mm to produce a negative electrode current collector 6. A 0.4 mm thick nickel-plated steel plate was pressed into a predetermined shape to produce a negative electrode terminal plate 5, and a flange 6 a of the negative electrode current collector 6 was welded to the negative electrode terminal plate 5. Then, the negative electrode current collector 6 was press-fitted into the hollow portion of the boss 7a of the gasket 7, and the sealing unit 9 was assembled.

(2) Preparation of Positive Electrode Manganese dioxide powder having an average particle size of 35 μm and graphite powder having an average particle size of 15 μm were mixed at a mass ratio of 94: 6, and 2 parts by mass of an alkaline electrolyte was added to 100 parts by mass of the mixture. After sufficiently stirring, the mixture was compression-molded to obtain a flake-shaped positive electrode mixture. The flake-shaped positive electrode mixture was pulverized into granules, and then pressed into hollow cylindrical pellets.

  As the alkaline electrolyte, an aqueous solution containing 35% by mass of potassium hydroxide and 2% by mass of zinc oxide was used.

(3) Preparation of Negative Electrode A gelling agent (sodium polyacrylate powder), an alkaline electrolyte, and a zinc alloy powder having an average particle diameter of 160 μm were mixed at a mass ratio of 0.8: 33.6: 65.6. Thus, a gelled negative electrode 3 was obtained.

(4) Assembly of Battery The positive electrode 2 was inserted into the battery case 1, and the positive electrode 2 was brought into close contact with the inner wall of the battery case 1 using a pressing jig. A bottomed cylindrical separator 4 was disposed in the hollow of the positive electrode 2. As the separator 4, a nonwoven fabric mainly composed of polyvinyl alcohol fiber and rayon fiber was used. After a predetermined time had passed after the alkaline electrolyte was injected into the separator 4, the gelled negative electrode 3 was filled in the separator 4. The outer periphery of the gasket of the sealing unit was placed near the opening of the battery case 1, and the opening end of the battery case 1 was bent inward to seal the battery, thereby completing the battery.

(5) Evaluation 120 batteries were prepared, and 30 sets of four batteries connected in series were prepared.
Four batteries connected in series were connected to a load (LED light). The battery was discharged by leaving it connected to the load until the LED stopped emitting light.

  After the discharged battery was stored in a room temperature environment for 12 weeks, the presence or absence of liquid leakage was examined. When liquid leakage was observed in at least one of the four batteries, it was evaluated that there was liquid leakage. The liquid leakage was evaluated for each of the 30 sets, and the ratio of the set evaluated as having the liquid leakage to the 30 sets was determined and evaluated as the liquid leakage rate.

  In the evaluation of the liquid leakage rate, a sealing unit 9 having a different combination of the water repellent material and the first region on which the water repellent layer was formed was produced, and the liquid leakage rate was evaluated for each of the produced batteries.

A water-repellent material used in each example, shows a contact angle theta ₁ with respect to the water below. Note that the contact angle of water of 6,6-nylon constituting the gasket with water is θ ₂ = 70 °.
PTFE: θ ₁ = 114 °
FEP: θ ₁ = 114 °
Bitumen: θ ₁ = 105 °
Polypropylene: θ ₁ = 94 °
Chlorosulfonated polyethylene (PE): θ ₁ = 80 °

When PTFE or FEP was used for the water-repellent material, a dispersion was prepared by adding a water-repellent material to a mixed solvent of ethyl nonafluoroisobutyl ether, ethyl nonafluorobutyl ether, and isopropanol to form a water-repellent layer.
When bitumen was used as the water-repellent material, a dispersion was prepared by adding a water-repellent material to xylene to form a water-repellent layer.
When polypropylene was used for the water-repellent material, a dispersion was prepared by adding a water-repellent material to a mixed solvent of isopropanol and water to form a water-repellent layer.
When chlorosulfonated polyethylene was used for the water-repellent material, a dispersion was prepared by adding a water-repellent material to a mixed solvent of trichloroethane and ethylene glycol monobutyl ether to form a water-repellent layer.

Further, for comparison, a sealing unit 9 was prepared in which hydrophilic polyvinyl alcohol (PVA) (θ ₁ = 36 °) was applied to a predetermined region on the inner surface of the gasket instead of the water repellent material, and the liquid leakage rate was evaluated. did. As the dispersion, an aqueous PVA solution was used.

In each of the examples and the comparative examples, the first region in which the water-repellent layer was formed had ten patterns as shown in FIGS. In FIG. 3A, no water-repellent layer was formed. In FIG. 3B, a water-repellent layer is formed only on the inner surface of the thin portion 8. FIGS. 3F to 3H correspond to the arrangement of the water-repellent layer in the example.
3 (c) to 3 (i), the water-repellent layer is formed on the inner surface of the connecting portion, in an annular region where the boundary position P with the boss portion is the inner peripheral end and the first position Q1 is the outer peripheral end. did. In addition, in FIGS. 3D to 3I, the water-repellent layer is formed in a cylindrical region having a height from the boundary position P to the second position Q2 on the outer peripheral wall surface of the boss.

In FIG. 3 (c), in consideration of the positional relationship of the contact area between the separator 4 and the connecting portion 7c after the battery is assembled, the water-repellent layer is set so that the first position Q1 is located on the outer boundary of the contact area. Was formed. No water-repellent layer was formed on the outer peripheral wall surface of the boss.
In FIG. 3D, the water-repellent layer is formed in the same manner as in FIG. 3C so that the first position Q1 is located at the outer peripheral boundary of the contact area. Further, a water-repellent layer was also formed on the outer peripheral wall surface of the boss portion, but the height H2 at the second position Q2 was higher than the height H1 at the first position.
In FIG. 3 (e), considering the positional relationship of the contact area between the separator 4 and the connecting portion 7c after assembling the battery, the first position Q1 is located on the inner peripheral side of the contact area. A layer was formed. The distance between the first position Q1 and the contact area was set to 1.1 mm. A water-repellent layer was also formed on the outer peripheral wall surface of the boss, and the height H2 at the second position Q2 was equal to the height H1 at the first position.

In FIG. 3F, as in FIG. 3E, the water-repellent layer is formed such that the first position Q1 is located on the inner peripheral side of the contact area. The distance between the first position Q1 and the contact area was set to 1.0 mm. A water-repellent layer was also formed on the outer peripheral wall surface of the boss, and the height H2 at the second position Q2 was equal to the height H1 at the first position.
In FIG. 3G, as in FIG. 3D, the water-repellent layer is formed such that the first position Q1 is located on the outer peripheral boundary of the contact region. A water-repellent layer was also formed on the outer peripheral wall surface of the boss, and the height H2 at the second position Q2 was equal to the height H1 at the first position.
In FIG. 3H, in FIG. 3G, the height H2 of the second position Q2 is changed to a position lower than the height H1 of the first position Q1, and the water-repellent layer is formed on the entire outer peripheral wall surface of the boss portion. Formed.

In FIG. 3 (i), the water-repellent layer is formed such that the first position Q1 is located on the outer peripheral side of the contact area with the separator in FIG. 3 (h). The distance between the first position Q1 and the contact area was set to 0.5 mm.
In FIG. 3 (j), the water-repellent layer was formed on the entire inner surface of the gasket.

  Table 1 shows the evaluation results of the liquid leakage rate. From Table 1, it can be seen that when the following conditions (1) to (3) are satisfied, liquid leakage is suppressed.

(1) The water-repellent layer is formed on the inner peripheral portion of the inner surface of the connecting portion having the first position Q1 as the outer peripheral end, and the first position Q1 is set on the contact region between the connecting portion and the separator or the separation distance between the contact region and the separator. Is a position on the inner peripheral side of the contact area within 1 mm.
(2) The height H2 of the second position Q2 is equal to or less than the height H1 of the first position Q1. This means that a water-repellent layer is formed on the inner surface of the gasket having the height H1 or more when combined with (1).
(3) contact angle theta ₁ of the water-repellent layer is greater than the contact angle theta ₂ of the gasket.

  In Table 1, a comparison between groups using PTFE as the water-repellent material shows that a water-repellent layer was formed in the regions shown in FIGS. 3F to 3H that satisfied the above conditions (1) and (2). In some cases, a noticeable improvement in the leak rate was seen. The arrangement of the water-repellent layer in FIGS. 3C and 3D satisfying only the condition (1) and the arrangement of the water-repellent layer in FIGS. 3E and 3I satisfying only the condition (2) In the arrangement, although a slight effect of suppressing liquid leakage is observed as compared with the case where the water-repellent layer is not formed, the effect is not sufficient.

The contact angle theta ₁ to the water repellent material is greater than the contact angle theta ₂ of the gasket, in the example using the less than 90 ° chlorosulfonated polyethylene, the arrangement of the water-repellent layer shown in FIG. 3 (f) and FIG. 3 (g) , A liquid leak was observed in one of the 30 sets. However, when the water-repellent layer on the outer peripheral wall surface of the boss is formed in the arrangement shown in FIG. 3H so that the height H2 at the second position Q2 is lower than the height H1 at the first position Q1, No liquid was observed.

Further, when the contact angle theta ₁ to the water-repellent material with 90 ° or more materials, in the arrangement of the water-repellent layer as shown in FIG. 3 (f) ~ FIG 3 (h), liquid leakage was observed.

  The alkaline dry battery according to the embodiment of the present invention can be used as a power source for various electronic devices because it can suppress liquid leakage due to hydrogen generation during overdischarge.

  1: battery case, 2: positive electrode, 3: gelled negative electrode, 4: separator, 5: negative electrode terminal plate, 6: negative electrode current collector, 6a: flange portion, 7: gasket, 7a: boss portion, 7b: outer peripheral portion, 7c: connecting part, 8: thin part, 9: sealing unit, 10: exterior label, 11, water-repellent layer, 100: alkaline battery

Claims (6)

A battery case having an opening;
A positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, and a power generation element housed in the battery case,
And a sealing unit for closing the opening,
The sealing unit includes a negative electrode terminal plate, a negative electrode current collector joined to the negative electrode terminal plate, and a gasket,
The gasket includes a boss portion through which the negative electrode current collector penetrates, an outer peripheral portion in contact with an opening end of the battery case, and a connecting portion that connects the boss portion and the outer peripheral portion,
The connecting portion has a thin portion having an explosion-proof function,
A water-repellent layer is formed on an inner surface of the gasket facing the power generation element,
The inner surface of the gasket has a first region where the water-repellent layer is formed, and a second region where the water-repellent layer is not formed,
The first region includes an inner surface of the thin portion, and is located on an inner peripheral side of a first position Q1 on the inner surface of the connecting portion,
The second region is located on the outer peripheral side of the first position Q1,
When the height in the axial direction of the boss portion with respect to the bottom portion of the battery case at the first position Q1 is H1, the first region is located on the inner peripheral side with respect to the first position Q1, And including a region located at a height equal to or higher than H1;
The first position Q1 is located on a contact region S on the inner surface between the connecting portion and the separator, or the first position Q1 is located on the inner peripheral side of the contact region S and the The distance between the one position Q1 and the contact area S is within 1 mm,
The contact angle theta ₁ with respect to water of the water-repellent layer is greater than the contact angle theta ₂ with respect to water of the gasket, alkaline batteries. The water-repellent layer is formed over a region having a height from a boundary position P between the boss portion and the connection portion to a second position Q2 on an outer peripheral wall surface of the boss portion,
The alkaline dry battery according to claim 1, wherein a height H2 of the boss portion in the axial direction with respect to a bottom portion of the battery case at the second position Q2 is lower than the height H1. The alkaline dry battery according to claim 1, wherein the contact angle θ ₁ is 90 ° or more.   The alkaline dry battery according to any one of claims 1 to 3, wherein the connecting portion is inclined such that an outer circumferential side of the connecting portion approaches the power generating element from an inner circumferential side. The thin portion is provided in an inner peripheral region of the connecting portion adjacent to the boss portion,
5. The alkaline dry battery according to claim 1, wherein the connecting portion is connected to the boss at the thin portion. 6.   The alkaline dry battery according to any one of claims 1 to 5, wherein the inner surface of the connecting portion has a concave portion formed by the thin portion.

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